Interferometric lasers can emit light over a wide range of wavelengths. If designed and wired in a suitable manner, they are electrically tunable over a wavelength range of more than 50 nm and are therefore ideally suited for many tasks in optical communications. An article by M. Schilling et al in IEEE Journal of Quantum Electronics, Vol. 26, No. 6, June 1993, describes an asymmetric Y-laser in detail.
Interferometric lasers contain at least 3 mirrors or reflection areas. These are required for the respective laser's internal filtering function. Both diescrete coupling and monolithic coupling of a waveguide to one of the mirrors requires a semiconductor-air-semiconductor transition, which is subject to large coupling losses. If during monolithic integration a more efficient transition is provided at one of the 3 mirrors, e.g. by a reflection grating area in a continuous or butt-coupled waveguide, the filtering function of the loser will be affected and its original wide tuning range will be restricted.